69 research outputs found
Charge Pumping Through a Single Donor Atom
Presented in this paper is a proof-of-concept for a new approach to single
electron pumping based on a Single Atom Transistor (SAT). By charge pumping
electrons through an isolated dopant atom in silicon, precise currents of up to
160 pA at 1 GHz are generated, even if operating at 4.2 K, with no magnetic
field applied, and only when one barrier is addressed by sinusoidal voltage
cycles.Comment: 14 pages, 10 figures, few changes in the text and in figure 8, New J.
Phys. (2014) at pres
Interface Trap Density Metrology of state-of-the-art undoped Si n-FinFETs
The presence of interface states at the MOS interface is a well-known cause
of device degradation. This is particularly true for ultra-scaled FinFET
geometries where the presence of a few traps can strongly influence device
behavior. Typical methods for interface trap density (Dit) measurements are not
performed on ultimate devices, but on custom designed structures. We present
the first set of methods that allow direct estimation of Dit in
state-of-the-art FinFETs, addressing a critical industry need.Comment: 9 pages, 4 figures, *G.C.T. and A.P. contributed equally to this wor
Dopant metrology in advanced FinFETs
Ultra-scaled FinFET transistors bear unique fingerprint-like device-to-device
differences attributed to random single impurities. This paper describes how,
through correlation of experimental data with multimillion atom tight-binding
simulations using the NEMO 3-D code, it is possible to identify the impurity's
chemical species and determine their concentration, local electric field and
depth below the Si/SiO interface. The ability to model the
excited states rather than just the ground state is the critical component of
the analysis and allows the demonstration of a new approach to atomistic
impurity metrology.Comment: 6 pages, 3 figure
Magnetic Field Probing of an SU(4) Kondo Resonance in a Single Atom Transistor
Semiconductor nano-devices have been scaled to the level that transport can
be dominated by a single dopant atom. In the strong coupling case a Kondo
effect is observed when one electron is bound to the atom. Here, we report on
the spin as well as orbital Kondo ground state. We experimentally as well than
theoretically show how we can tune a symmetry transition from a SU(4) ground
state, a many body state that forms a spin as well as orbital singlet by
virtual exchange with the leads, to a pure SU(2) orbital ground state, as a
function of magnetic field. The small size and the s-like orbital symmetry of
the ground state of the dopant, make it a model system in which the magnetic
field only couples to the spin degree of freedom and allows for observation of
this SU(4) to SU(2) transition.Comment: 12 pages, 10 figures, accepted for publication in Physical Review
Letter
Studying Parallel Evolutionary Algorithms: The cellular Programming Case
Parallel evolutionary algorithms, studied to some extent over the past few years, have proven empirically worthwhile—though there seems to be lacking a better understanding of their workings. In this paper we concentrate on cellular (fine-grained) models, presenting a number of statistical measures, both at the genotypic and phenotypic levels. We demonstrate the application and utility of these measures on a specific example, that of the cellular programming evolutionary algorithm, when used to evolve solutions to a hard problem in the cellular-automata domain, known as synchronization
Comment: Superconducting transition in Nb nanowires fabricated using focused ion beam
In a recent paper Tettamanzi et al (2009 Nanotechnology \bf{20} 465302)
describe the fabrication of superconducting Nb nanowires using a focused ion
beam. They interpret their conductivity data in the framework of thermal and
quantum phase slips below . In the following we will argue that their
analysis is inappropriate and incomplete, leading to contradictory results.
Instead, we propose an interpretation of the data within a SN proximity model.Comment: 3 pages, 1 figure accepted in Nanotechnolog
A planar Al-Si Schottky Barrier MOSFET operated at cryogenic temperatures
Schottky Barrier (SB)-MOSFET technology offers intriguing possibilities for
cryogenic nano-scale devices, such as Si quantum devices and superconducting
devices. We present experimental results on a novel device architecture where
the gate electrode is self-aligned with the device channel and overlaps the
source and drain electrodes. This facilitates a sub-5 nm gap between the
source/drain and channel, and no spacers are required. At cryogenic
temperatures, such devices function as p-MOS Tunnel FETs, as determined by the
Schottky barrier at the Al-Si interface, and as a further advantage,
fabrication processes are compatible with both CMOS and superconducting logic
technology.Comment: 6 pages, 4 figures, minor changes from the previous version
A hybrid double-dot in silicon
We report electrical measurements of a single arsenic dopant atom in the
tunnel-barrier of a silicon SET. As well as performing electrical
characterization of the individual dopant, we study series electrical transport
through the dopant and SET. We measure the triple points of this hybrid double
dot, using simulations to support our results, and show that we can tune the
electrostatic coupling between the two sub-systems.Comment: 11 pages, 6 figure
Linguistic summarization of time series data using genetic algorithms
In this paper, the use of an evolutionary approach when obtaining linguistic summaries from time series data is proposed. We assume the availability of a hierarchical partition of the time dimension in the time series. The use of natural language allows the human users to understand the resulting summaries in an easy way. The number of possible final summaries and the different ways of measuring their quality has taken us to adopt the use of a multi objective evolutionary algorithm. We compare the results of the new approach with our previous greedy algorithms
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